Automoble antenna with toroid coil and magnetic core



Nov. 27, 1962 I L. G. HORWlTT AUTOMOBILE ANTENNA WITH TOROID COIL AND MAGNETIC CORE Filed Oct. 5. 1954 5 Sheets-Sheet 1 I l lluqik "I INVENTOR lame/70 6f Homm'zt W M W ATTORNEYS Nov. 27, 1962 L. e. HORWITT 3,066,292

AUTOMOBILE ANTENNA WITH TOROID 001 AND MAGNETIC CORE Filed Oct. 5, 1954 3 Sheets-Sheet 2 1N VENT OR Z; a u Pence G. Hora/2 1.

M \4QAML ATTORNEYS Nov. 27, 1962 L. G. HORWITT AUTOMOBILE ANTENNA WITH TOROID COIL AND MAGNETIC CORE 3 Sheets-Sheet 5 Filed Oct. 5, 1954 IN VENTOR ATTORNEYS United States Patent AUTOMOBLE ANTENNA WITH TORUID COIL AND MAGNETIC CORE Laurence G. Horwitt, New Haven, Conn., assignor t0 Case-o Products Corporation, Bridgeport, Conn., a corporation of Connecticut Filed Oct. 5, 1954, Ser. No. 460,447 Claims. (Qt. 343-717) This invention relates to antennas, and more particularly to coil-type antennas which are adaptable for use on automobiles and other vehicles, for the reception of radio or kindred waves.

Antennas have been proposed in the past, comprising small coils of wire which were connected to the input side of receiving or other electronic apparatus. in some of these coils, cores formed of powdered iron were provided, it being found that the powdered iron core greatly increased the sensitivity of the antenna. Generally the coils of these prior antennas were substantially in the form of helices, and the antennas thus constructed had marked directional properties. There has been also proposed in the past a coil-type antenna which is substantially nondirectional this being accomplished by winding the coil in the form of a toroid.

The present invention deals with improvements in these prior antennas, and one object of the invention is to provide a novel and improved nondirectional radio antenna of the coil type above mentioned, which is extremely sensitive in its response to signals from all directions.

Another object of the invention is to provide an improved coil-type antenna in accordance with the forcgoing, which is housed in a sturdy and economical casing that both prevents damage to the antenna and at the same time increases the sensitivity thereof.

A still further object of the invention is to provide an improved, nondirectional coil-type antenna which is particularly inexpensive and economical to manufacture and produce.

Still another object of the invention is to provide a novel, coil-type antenna in accordance with the foregoing, which is particularly adaptable to use with an automobile or other vehicle having metal construction, and which utilizes such metal construction to advantage in its operation.

I accomplish the above objects by the provision of a novel antenna structure comprising a conducting coil having a ring-like configuration, a portion of said coil being of straight section and containing the powdered iron core. I enclose the coil in a ring-shaped housing of nonmagnetic metal which is ungrounded and insulated from any metal framework or supporting structure on which the antenna is carried.

By the provision of the insulated, nonmagnetic metal housing the signal strength or pickup of the antenna is materially increased, and by virtue of the coil having a straight section the magnetic core of powdered material may be made straight and thus fabricated more economically.

Other features and advantages will hereinafter appear.

In the accompanying drawings:

FIG. 1 is a bottom View of the improved antenna of this invention.

FIG. 2 is a vertical section taken on line 2-2 of FIG. 1.

FIG. 3 is a side view of an automobile having incorporated in it the antenna of the invention.

FIG. 4 is a bottom View of the coil assembly of the antenna.

FIG. 5 is a bottom view of the pickup coil of the coil assembly of FIG. 4.

ice

FIG. 6 is a bottom View of the coupling coil of the assembly of FIG. 4.

FIG. 7 is a side view of a core element prior to being bent, for the coil of FIG. 5.

FIG. 8 is a detail showing a joint between two sections of FIG. 7 prior to the joint being taped.

FIG. 9 is a side view of the coil of FIG. 5 prior to the coil being formed into a ring-like shape.

FIG. l0 is a fragmentary radial sectional view taken on line lit-10 of FIG. 1.

FIG. 11 is a schematic diagram of the circuit connections of the antenna.

FIG. 12 is a perspective view of a mounting bracket for the antenna.

FIG. 13 is a perspective view of the completely assembled antenna.

The improved coil-type antenna of the present invention comprises a coil assembly 2% see FIG.'4, including a pickup coil 21 (FIG. 5) which is wound of thin metal ribbon 22, preferably copper, said coil having a configuration, including an axially straight section 23 such that the axis of the coil is substantially in the form of the letter D. Joining the straight section 23 is a curved or partially circular section 24. Actually the shape of the coil 21 and its axis is formed by the major portion of a circle, as represented by the coil section 24, the ends of which are connected by a straight line as represented by the coil section 23.

While the shape shown in FIGS. 4 and 5 is not exactly in the form of the letter D it is substantially so, and the shape may be varied appreciably without departing from the spirit of the invention. The essential characteristic, as regards the shape of the coil 21 is that it is substantially in the form of a ring having a straight portion or section, the remaining portions or sections being either circular, polygonal or of any other geometrical figure or pattern similar to or suggestive of the letter U. The coil 21 is provided with a magnetic core 25, which may be advantageously formed of powdered iron commonly known as Ferrite, and by the provision of the straight section 23 in accordance with the invention the magnetic core 25 may consist of a straight length of powdered iron or equivalent material.

Accordingly the producing of the iron core 25 may be done much more economically than if the core were made to have a circular or curved configuration as in prior proposed constructions. Referring to FIG. 5 the core 25 shown therein is disposed within the straight section 23 of the antenna coil 21, and the remainder of the coil 21 is devoid of magnetic core material.

In constructing the coil 21 I provide a straight length of corrugated cardboard 26 having a recess 27 at one end adapted to receive an end of the core 25. The corrugated board 26 has the same width as the core 25 and is secured to the core by wrapped-around tape 28 as shown in FIG. 7. The entire length of the core 25 is now wrapped with insulating tape. On this assemblage of core and corrugated board I wind the coil 21 of conducting ribbon. The coil 21 of the ribbon 22 may be wound in a coil winding machine or any other suitable mechanism, after which the curved section 24 of the coil may be formed by suitably bending the wound assemblage. The free ends of the core 25 and corrugated board 26 may be secured together by wrapped-around tape 3!), as shown in FIG. 5.

I have found that a coil antenna made in accordance with the above construction has advantageous, nondirectional pickup properties by virtue of its ring-like shape, and is at the same time sensitive to weak signals by virtue of the magnetic core 25. The inclusion of the straight section 23 as part of the ring does not materially or appreciably adversely affect the performance or sensitivity of the antenna coil, while at the same time it enables the core to be economically formed in a straight shape.

In conjunction with the coil 21 I provide a D-shaped coupling coil 31, FIG. 6, which is wound of wires bunched together, the coil 31 being attached to the bottom edge of the coil 21 by tapes 32. The coil 31 is tapped at a point between its ends, and the tap, indicated as 33 in FIG. 6, is brought out and constitutes the lead-in connec tion of the antenna. The end wires 34 and 35 of the coil 31 are electrically connected to the ends 36 and 37 respectively of the ribbon coil 21. The coil assembly 20 as shown in FIG. 4 is preferably dipped in a hardening, insulating compound after its completion.

The coil 21 may advantageously'have 59 turns of ribbon, and may be of a size such that its straight section 23 is approximately five and one-half inches long and the inside radius of the circular section 24 is approximately three and one-half inches. The coil 31 may have 23 turns, and the tap 33 may belocated between the second and third turns. These connections and relations are in part illustrated in.FIG. 11.

I have found that an advantageous casing may be provided for the antenna coil assemblage above described, which is not only protective and provides an advanta' geous mounting for the coil assemblage but also increases the sensitivity and ability of the coil to pick up radio signals.

Referring to FIGS. 1 and 2 a metal, ring-shaped casing 40 is provided, formed of nonmagnetic metal such as aluminum, said casing having substantially a U-shaped section as shown in FIG. 2 and being provided with a metal cover 41 which is fitted over the open side of the casing 40 and permanently attached thereto by fianging and clinching the edges or lips of the casing around and over the cover. The casing 40 is provided with threaded mounting studs 42, and after the antenna coil assemblage 20 is placed in the casing the latter is filled with an insulating compound which securely positions the coil assembly, rigidly fastens it to the casing and prevents moisture from reaching the coils. To position the coil assembly 20 in the casing prior to filling With compound, U- shaped spacers 39 of insulating material may be used.

The lead from the coil assembly 20, constituting the tap 33, is attached to a pin 43 of a connector fitting 44 which is secured to the outer peripheral surface of the casing 40 adjacent one end of the straight section thereof. The antenna lead-in wire 45, carried in a grounded shielding sheath 46 is connected to a sleeve 47 in the fitting 44, which telescopes and contacts the pin 43. The grounded sheath 46 is securely fastened to an insulating portion 48 of the fitting 44 by means of a spun metal collar 49. The collar 49 and sheath 46, however, are insulated from the metal casing 40.

Intermediate the ends of the curved section of the casing 40 a connector fitting 50 is provided, mounted on the exterior periphery of the casing, said fitting insulatedly carrying a stud 51 connected by a wire 52 to the ribbon coil 21 of the antenna. The wire 52 may be soldered or otherwise suitably secured to the antenna ribbon, as desired. The stud 51 supports a slender rod 53 which acts as an additional pickup element, found to be advantageous for weak signals.

I have found that by the provision of the nonmagnetic metal casing 40 a secure mounting may be provided for the coil assembly of the antenna while at the same time, by an action at present not clearly understood, the sensitivity of the antenna is increased. It is important that the casing 40 be insulated from the ground or frame of the automobile on which the antenna is mounted, and this may be done by any suitable type of insulating mounting bracket. The fact that the casing 40 is in the shape of a ring plays a part in the increased sensitivity obtained. Also it enables an economical use of insulating compound which seals the coil assembly from moisture and rigidly secures it within the casing. The casing 30 additionally provides an effective protective covering, preventing damage to the antenna coil assembly during use.

FIG. 3 shows the antenna of the invention, indicated by the letter A, installed on an automobile below and on a forward portion of the chassis, and connected with the radio set B.

For the purpose of mounting the antenna a U-shaped bracket 54 is provided, having outwardly ofiset feet 55 which are clamped between insulating washers 56, FIG. 2, carried by the studs 42.

Variations and modifications may be made within the scope of the claims and portions of the improvements may be used without others.

1 claim:

1. A substantially nondirectional radio antenna comprising a conducting coil wound about an axis and having a configuration, including an axially straight section, such that the axis of the coil is substantially in the form of the letter D; and a straight magnetic core disposed in the straight section of the coil.

2. A substantially nondirectional radio antenna comprising a conducting coil wound about an axis and having a configuration, including an axially straight section, such that axis of the coil is in the form of a loop having a straight portion; and a straight magnetic core disposed in the straight section of the coil.

3. A substantially nondirectional radio antenna comprising a conducting coil wound about an axis and having a configuration, including an axially straight section, such that the axis of the coil is in the form of a loop having a straight portion; a straight magnetic core disposed in the straight section of the coil; and a ringshaped, nonmagnetic metal casing having a straight section, enclosing said coil and spaced therefrom.

4. A substanitally nondirectional radio antenna comprising a conducting coil wound about an axis and having a configuration, including an axially straight section, such that the axis of the coil is in the form of a loop having a straight portion; a straight magnetic core disposed in the straight section of the coil; a ring-shaped, nonmagnetic metal casing having a straight section, enclosing said coil and spaced therefrom; a lead Wire passing through said casing and connected to the coil; and a grounding shield around said lead wire and insulated therefrom and from the casing.

5. A substantially nondirectional radio antenna comprising a conducting coil wound about an axis and having a configuration, including an axially straight section, such that the axis of the coil is in the form of a loop having a straight portion; a straight magnetic core disposed in the straight section of the coil; a continuous, unbroken ring-shaped, nonmagnetic, metallic casing having a straight section enclosing said coil and spaced therefrom which increases the sensitivity of the coil, a lead wire passing through said casing and connected to the coil; a grounding shield around said lead Wire and insulated therefrom and from the casing; a metal mounting bracket; and means insulatedly securing the mounting bracket to said casing to enable the latter to be mounted on the surface of an automobile and insulated therefrom.

References Qited in the file of this patent UNITED STATES PATENTS 2,077,822 Baker Apr. 20, 1937 2,146,654 Shea et al Feb. 7, 1939 2,192,321 Meier Mar. 5, 1940 2,217,989 Morgan Oct. 15, 1940 2,375,593 Sontheimer May 8, 1945 2,595,244 Goss et al. May 6, 1952 2,602,891 Stelzer July 8, 1952 2,863,147 Berlin Dec. 2, 1958 FOREIGN PATENTS 361,234 Italy July 16, 1938 

